Rapid Synthesis of Polyfunctionalized Pyrano[2,3-c]pyrazolesviaMulticomponent Condensation in Room-Temperature Ionic Liquids

Efficient and green synthesis of 4H-pyrans and 4H-pyrano[2,3-c] pyrazoles catalyzed by task-specific ionic liquid [bmim]OH under solvent-free conditions

“…Recently, pyrano [2,3-c]pyrazoles have been synthesized using *Corresponding author. Email: jmkhurana1@yahoo.co.in catalysts like triethyamine (28), Mg/Al hydrotalcite (29), glycine (30), and L-proline in [bmim]BF 4 (31) whereas the synthesis of 2-amino-4H-pyrans has been reported using catalysts like Cu(II)oxymetasilicate (34), ZnO/MgO solid sample containing ZnO nanoparticles (35), silica nanoparticles (36), piperidine (37), magnesium oxide (38), or 1,1,3, 3-tetramethylguanidine (TMG) (39) and also under microwaves exposure (40) in one pot reactions. Though there are many reports on the synthesis of 4H-pyrans and 4H-pyrano [2,3-c]pyrazoles.…”

Silica-coated magnetic NiFe2O4 nanoparticles-supported H3PW12O40; synthesis, preparation, and application as an efficient, magnetic, green catalyst for one-pot synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-c]pyrazole derivatives

“…It was found that use of PWA, SiO 2 , and NiFe 2 O 4 @SiO 2 (NFS) without catalyst resulted in poor product yields, irrespective of the conditions (Table 1, entries [5][6][7][8]. To determine the optimum amount of catalyst (Table 1, entries 9, 10) we performed the reaction with different amounts of Silica-coated magnetic NiFe 2 O 4 nanoparticles-supported… Silica-coated magnetic NiFe 2 O 4 nanoparticles-supported… [20] catalyst; we found that 0.03 g NFS-PWA effectively catalyzed the reaction and resulted in the highest yield ( Table 1, entry 1). Moreover, this reaction occurred at room temperature (25°C) and impure product was achieved (Table 1, entry 11).…”

“…The most convenient methods are bicomponent condensation of 1,3-dicarbonyl compounds (1,3-cyclohexanedione or 5,5-dimethyl-1,3-cyclohexanedione) with a-cyanocinnamonitrile [14][15][16][17][18], or one-pot, three-component reaction of aldehydes, malonitrile, and 1,3-dicarbonyl compounds (1,3-cyclohexanedione or 5,5-dimethyl-1,3-cyclohexanedione) or 3-methyl-1-phenyl-2-pyrazoline-5-one, in the presence of a variety of catalysts [19]. Highly efficient synthesis of 4H-pyrano [2,3-c]pyrazole by fourcomponent cyclocondensation of hydrazine hydrate or phenylhydrazine, ethyl acetoacetate, aldehydes, and malonitrile in the presence of L-proline and [Bimim]BF 4 at 50°C has also been reported [20]. Catalysts used for one-pot, three-component reactions include piperidine [21], hexadecyltrimethyl ammonium bromide (HTMAB) [22], sodium bromide [23], ionic liquids [24][25][26][27][28][29], tetramethylammonium hydroxide [30], diammonium hydrogen phosphate [31], organocatalysts [32], sodium selenite [33], tetrabutylammonium bromide (TBAB) [34,35], polyaniline-silica gel [36], alum [KAl(SO 4 ) 2 Á12H 2 O] [37], rare earth perfluorooctanoates, e.g.…”

Microwave‐Assisted Organic Synthesis in Ionic Liquids

“…Khurana et al . synthesized 4 H ‐pyrano[2,3‐ c ]pyrazoles from cyclocondensation of hydrazine monohydrate or phenyl hydrazine, ethyl acetoacetate, aldehydes, and malononitrile in [BMIM][BF4] with catalytic quantities of l ‐proline (10 mol%) under MW exposure.…”